British physicist Cecil Powell studied under Ernest Rutherford and C. T. R. Wilson, and became a mid-20th century expert in the use of photographic emulsions to study nuclear particles, authoring two widely respected books on the subject. In 1947, using techniques of his design, the heavy subatomic particle pi-meson (or pion) in cosmic rays was discovered in Powell's laboratory, confirming the existence of mesons as predicted twelve years earlier by the Japanese physicist Hideki Yukawa. The actual discovery was made by a Brazilian student of Powell's, Cesare Lattes (1924-2005), but the credit and eventually the Nobel Prize in Physics went to Powell in 1950, a year after Yukawa received the same honor. Before marrying in 1932, Powell shared an apartment with another future Nobel laureate, Max Delbrück. He also studied volcanic phenomena and conducted high-altitude balloon investigations of cosmic rays.